This antenna relates generally to antennas for receiving or transmitting radio frequency energy and more particularly to broadband antennas which fit into relatively small volumes.
Antennas are widely used in many types of systems. The structure of the antenna affects its operating characteristics. As a result, antennas take on a variety of shapes. The particular shape is selected to meet the requirements of a system.
For certain systems, it is desirable to construct a broadband, circularly-polarized antenna which transmits or receives a beam of radio frequency energy over a wide angular range (i.e., a broad-beam antenna). The antenna must be relatively small and have a low manufacturing cost. Further, when many antennas are made, each should have substantially the same performance characteristics.
Crossed dipoles are often used to construct inexpensive broad beam antennas. Crossed dipoles are relatively broad beamed. In addition, the phase of signals applied to the different dipoles can be varied to produce signals with linear or circular polarizations.
One variation on the crossed dipole antenna is called a notch antenna. The four dipole halves are constructed from rectangular sheets of conducting material mounted perpendicular to a ground plane which acts as a reflector. The corner of each rectangular sheet near the center of the structure is cut out to form notches.
Such antennas, while adequate for some applications, did not provide adequate gain or bandwidth for some applications.